Property-Based Testing with PropEr, Erlang, and Elixir

Stateful Properties

Here’s the code to make the cache code sequential:

Elixir                code/StatefulProperties/elixir/pbt/lib/cache_fixed.ex

defmodule Cache do

use GenServer

## Public API ##
def start_link(n) do
  GenServer.start_link(__MODULE__, n, name: __MODULE__)
end

def stop() do
  GenServer.stop(__MODULE__)
end

def find(key) do
  case :ets.match(:cache, {:_, {key, :"$1"}}) do
    [[val]] -> {:ok, val}
    [] -> {:error, :not_found}
  end
end

  def cache(key, val) do
    GenServer.call(__MODULE__, {:cache, key, val})
  end

  def flush() do
    GenServer.call(__MODULE__, :flush)
  end

  ## GenServer callbacks ##
  def init(n) do
    :ets.new(:cache, [:public,